1. Field of the Invention
The present invention relates to an energy absorbing device for use with a seat belt system of a vehicle, such as an automobile, to absorb the kinetic energy of a passenger during a collision of the vehicle so as to prevent the passenger from being injured.
2. Description of the Prior Art
As a means for absorbing the kinetic energy of a passenger during a collision of a vehicle, an energy absorbing device for use with a vehicular seat belt system has been known which utilizes an elongated member of a metal connected to the seat belt so that the metal member is plastically deformed by the tension produced in the seat belt by a shock load caused by the collision thereby to absorb the kinetic energy of the passenger.
More specifically, one type of the known energy absorbing devices has a casing having a pair of parallel faces and a folded web of a metal associated with the casing such that the folded part of the metal web extends between the two faces of the casing with one end of the web secured to the casing and the other end extending therefrom. On collision, there is produced a relative movement between the casing and the metal web so that the folded part of the web is subjected to plastic deformation. Another type of the energy absorbing devices of the prior art comprises a corrugated sheet metal having one end secured to a part of the vehicle and the other end connected to an end of a seat belt so that the corrugated sheet metal is plastically deformed and elongated by an energy produced during a collision of the vehicle.
The folded metal web and the corrugated sheet metal employed in the prior art energy absorbing devices are large-sized and are difficult to install within a limited space in a vehicle. In addition, the large-sized members will lead to the increase in the weight of the vehicle and thus are undesirable from the view points of saving material and also minimizing the fuel consumption of the vehicle.